Chromatographic chamber



iinited StatesPatent 2,873,660 2/1959 Land et a1 95/96X 3,192,847 7/1965 Ener 95/97 3,427,949 2/l 969 Knight et al. 95/96X FOREIGN PATENTS 820,765 9/1959 Great Britain 95/96 Primary Examiner-John M. Horan Assistant Examiner-Fred L. Braun Attorneys-Walter O. Hodsdon, Paul R. Holmes and Alfred P.

Lorenzo ABSTRACT: A chromatographic developing chamber formed of a pair of stiff, generally rectangular, oppositely disposed, wall members open at one end for introduction of a chromatographic sheet and closed at the other end to form an elution solvent reservoir. One or more indentations are formed in the vicinity of the reservoir to hold the chromatographic sheet in place, and two rows of indentations, each row preferably having a channel on each side thereof, are formed between the reservoir and'the open end of the chamber to assist in holding the sheet and to prevent nonuniform rise of solvent.

SHEET 2 OF 2 INVENTORS ANDRE El? LEST/EN/VE GEORGES M. BOUD/N ATTORNEYS 1 CHROMATOGRAPHIC CHAMBER BACKGROUND OF THE INVENTION 1. Field of the Invention 1 This invention relates to chromatographic apparatus and, in particular, it relates to an improved simplified chromatographic-developing chamber especially adapted for. use in thin-layer chromatography.

. 2. Description of the Prior Art A modern form of chromatography is the so-called thin-' layer chromatography. The name is based upon the use of an adsorption agent in the form of a thin-layer on an inert support. This arrangement possesses a number of known advantages as compared to other chromatographic techniques such as an adsorption column, paper chromatography, etc.

In orderto improve the quality of chromatographic separation it is desirable to utilize a chamber of small capacity so that the atmosphere therein will reach equilibrium very quickly with the solvent vapors. It is also desirable to provide a simple and compact chamber for carrying out thin-layer chromatographic analysis. Such a chamber is disclosed and claimed in copending Pat. application Ser. No. 741,035 filed June 28, I968, by Pierre L. Clement and Andre F. P. Lestienne, assigned to the same assignee as the present application and issued Sept. 2, 1969, as US. Pat. No. 3,464,560. The chambers shown in the said Clement and Lestienne application include sleeves of suitable materials, e.g. polyesters such as polyethylene terephthalate or the like, and the chambers shown therein may or may not include an elution solvent located in a capsule within the chamber.

Although the chambers shown in saidcopending application are improved over those known previously, it is desirable to improve the operation of these devices still more by arranging and shaping the chambers so that the liquid solvent rises regularly with its front surface remaining horizontal for the full duration of the chromatographic analysis procedure, and so that no capillary effects, etc. will act to accelerate the rise I of liquid along the sides of the chromatographic sheet.

- SUMMARY or THE INVENTION The purpose of this invention is to provide an improved compact chromatographic chamber, which includes improved structure for retaining the chromatographic sheet within the chamber and for permitting the proper and accurate migration of the elution solvent during chromatographic analysis, and to provide a simple and convenient method for manufacture thereof.

According to the present invention there is provided a thin compact chromatographic chamber formed by a pair of generally rectangular, substantially parallel and symmetrical sides sealed together around three edges and open at the top. Preferably, the material of the sides should be as transparent as possible, (or at least translucent) to allow the operator to see the different separation phases through the sides, it should be thermoplastic to permit shaping after heat softening, it should be stiff at normal temperatures to permit accurate positioning of the chromatographic sheet relative to the sides, and it should be chemically inert and thereby unaffected by elution solvent or other chemicals employed during the chro-. matographic analysis procedure.

The chamber of this invention is designed to provide a uniform rise of solvent on the adsorbent layer of the 'chromatographic sheet while preventing irregular rise of solvent by capillary action along the sides or back of the sheet. To accomplish this objective, the chamber includes sets of indentations for holding the chromatographic sheet at a plurality of contact points. Aside from these contact points, the sheet remains substantially free from contact with the internal walls of the chamber. First, a set of indentations is located in the vicinity of the reservoir, centrally of the chamber. Secondly, two rows of indentations are provided extending longitu dinally from the reservoir towards the open end of the chamber, each row comprising a plurality of spaced indentaill tions for pinching the sheet therebetween. Between the two rows of longitudinally extending indentations there is provided a chimney" area wherein the sheet remains completely spaced from the internal walls of the chamber.

Longitudinally extending enlarged grooves or channels are provided on each side of each longitudinally extending row of indentations. Next, a transversely extending enlarged groove or channel is located immediately above the first set of indentations and is in fluid communication with both the reservoir and the longitudinally extending enlarged grooves.

The first set of indentations may comprise a single large indentation extending across a major portion of the reservoir or it may comprise a plurality of spaced indentations.

A plurality of apertures are provided in the chimney area of the chamber between the two longitudinally extending rows of indentations for application of the sample material to be tested. In addition, an apertureis provided in the area of the enlarged transversely extending groove for introduction of elution solvent.

Thus, it is an object of this invention to provide an improved chromatographic chamber which overcomes disadvantages of chambers known heretofore.

It is another object of this invention to provide an improved compact simplified chromatographic chamber constructed and arranged to provide a uniform rise of elution solvent on the adsorbent layer and to prevent an irregular rise of elution solvent along the side or back of the chromatographic sheet.

It is still another object of this invention to provide an improved chromatographic chamber wherein the chromatographic sheet is held withinthe chamber at aplurality of contact points formed as indentations in the sides of the chamber and wherein the sheet is otherwise substantially free from contact with the interior walls of the chamber.

Other objects and the attendant advantages of the present invention will become apparent from the detailed description to follow together with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS In the drawings:

FIG. 1 is an elevational view of a chromatographic chamber according to the present invention.

FIG. 2 is a vertical sectional view taken along line 2-2 of FIG. 1.

FIG. 3 is a horizontal sectional view taken along line 3-3 of FIG. 1. I 7

FIG. 4 is a horizontal sectional view taken along line 4-4 of FIG. 1.

FIG. 5 is an elevational view illustrating a second embodiment of the invention.

FIG. 6 is a vertical sectional view taken'along line 6-6 of FIG. 5.

FIG. 7 is a horizontal sectional view taken along line 7-7 of FIG. 5.

FIG. 8 is a horizontal sectional view taken along line 8-8 of FIG. 5. I

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIGS. 14 illustrate a first embodiment of theinvention comprising a chromatographic chamber 20 having two identical generally parallel rectangular sides 21a and 21b, which are symmetrical about their longitudinal axis. These sides (also referred to herein as wall members) are formed of a material preferably as transparent as possible (or at least translucent) and are formed in the same mold or identical molds of a thermoplastic material which is shaped afterheat softening. The thermoplastic materiahwhen formed, should be stiff at room temperature and inert in and unaffected by the elution solvents. The two sides have flanges on three edges which are heat sealed together along the two longitudinal edges and along the bottom edge at seal 22 leaving an open top 23. By way of example, a suitable material for forming the sides would be polyester sheeting such as unoriented polyethylene terephthalate, polyamides, polyolefins (low pressure polyethylenes or polypropylenes), stiff polyvinyl chloride, etc. and even glass, if practical in use. A suitable thickness for the sides would be, for example, 0.3-0.5 millimeters.

The space between the two sides 21a and 21b should be very thin so as to provide a small volume so that the solvent vapors reach equilibrium very quickly with the atmosphere in the chamber.

One feature of the invention is a means for mounting a chromatographic sheet in the chamber so that it is substantially free from contact with the interior walls of the chamber. In this manner, uniform migration of the solvent along the adsorbent layer of the chromatographic sheet is provided, and, further, irregular movement of the solvent by capillary action along the sides or back of the sheet is prevented.

This purpose is accomplished by providing, first, a series of indentations 25 in the vicinity of the reservoir 24. These indentations are provided in cooperating pairs, one on each side. They project into the chamber and extend close to the center plane of the chamber passing through the three seamed edges, with corresponding indentations being close enough together to pinch therebetween thechromatographic sheet, thereby holding the same in the center of the chamber free from contact with the internal walls of the chamber except at the point where it is pinched by the indentations. As shown in FIG. 1, this first embodiment of the invention provides a plurality ofindentations in the vicinity ofthe reservoir.

The chromatographic sheet must also be centered in the chamber from the reservoir 24 to the opening 23. For this purpose a pair of discontinuous longitudinal rails 26a and 26b are provided from the vicinity of the reservoir 24 up to the opening 23 of the chamber. These rails 26a and 261) are also formed as a plurality of aligned pairs of indentations 27, each pair consisting of one indentation on each of the sides of the chamber extending approximately to the center plane of the chamber. In this manner the chromatographic sheet is retained in the center of the chamber substantially free from contact with the interior walls of the chamber while contacted only along a limited number of predetermined contact points.

The chromatographic analysis itself takes place in a chimney area 28 between the two rails 26a and 26b where the two sides 21a and 21b are spaced-apart from each other. The top of the chamber can be pinched closed by a clamp after insertion of the chromatographic sheet.

To keep the fluid from rising up along rails 26a and 26b by capillary action, there is provided in the interior faces of the wall members on each side of each rail 26a and 26b an enlarged longitudinally extending groove or channel 29a and 29b. These grooves allow fluid to drain downwardly to the reservoir.

An enlarged transverse groove or channel 30 is preferably provided across the chamber immediately above the first series of indentations 25, groove 30 being in fluid communication with both the channels 29a and 29b and with the reservoir 24. By filling the reservoir 24 up to a level including the enlarged groove 30, it is possible to provide an even starting front for the elution solvent as it migrates up the chromatographic sheet. In addition, this area provides a suitable reservoir for receiving drain liquid from the channels 29a and 29b.

An aperture or hole 31 is provided in the lower portion of the chamber for introducing solvent into the reservoir. The diameter of this aperture is such that it allows the passage of the tip of a syringe or a hypodermic needle. However, it must not be so large as to prevent or delay saturation of the chamber with the solvent vapor.

Near the upper portion of the chimney 28 there are provided a plurality of apertures or holes 32, 2 or 3 millimeters in diameter, facing the adsorbent layer of the chromatographic sheet. Through these apertures the samples to be analyzed may be placed upon. the adsorbent layer of the chromatographic sheet as it is introduced into the chamber. These apertures may also be just large enough to permit entry of the tip of a syringe or a hypodermic needle.

FIGS. 5-8 illustrate another embodiment of the present invention. The chamber shown in these figures is identical to the chamber of FIGS. l-4 except that the plurality of separate indentations 25 of FIGS. 1-4 are replaced by a single transversely extending indentation 125 in each wall member. Thus, like numerals have been employed to represent like parts except that the numerals of FIGS. 5-8 are in the series rather than the 10's series.

The single transversely extending indentation allows a uniform and sudden starting of the liquid rise throughout the useful width of the chromatographic sheet. The only other distinction in the embodiment of FIGS. 5-8 is the greater width of the chamber between the two-sealed longitudinal edges. It will be evident that the features of the invention can be applied to chambers of any desired length and width. In the chamber of FIGS. 5-8, as in the chamber of FIGS. 1-4, the various indentations center the chromatographic sheet in the chamber and assure the uniform rise of elution solvent along the sheet.

The chromatographic chamber described herein can be fabricated in a very simple and convenient manner. Thus, for example, the two identical wall members can be molded from sheets of a thermoplastic material, positioned in opposing relationship, and then heat sealed together along the two longitudinal edges and along one transverse edge.

The invention has been described in detail with particular reference to preferred embodiments thereof, but it will be understood that variations and modifications can be effected within the spirit and scope of the invention as described hereinabove and as defined in the appended claims.

We claim:

1. An apparatus for use in developing a thin-layer chromatographic sheet, comprising a pair of generally rectangular wall members disposed opposite and spaced from each other to form therebetween a thin chamber for enclosing the chromatographic sheet; said members being sealed together along both longitudinal edges and along one transverse edge so that said chamber is closed at one end to provide a reservoir for an elution solvent and open at the other end to permit introduction of the chromatographic sheet; each of said members having a plurality of indentations therein projecting into said chamber and located opposite corresponding indentations in the opposing member to grip the chromatographic sheet therebetween; said plurality of indentations comprising two longitudinal rows of spaced indentations one of which rows is adjacent each of said longitudinal edges and at least one additional indentation between said longitudinal rows adjacent said reservoir; whereby the chromatographic sheet is supported in said chamber with one end thereof in said reservoir.

2. A chromatographic developing apparatus as described in claim 1 wherein said at least one additional indentation consists of a transverse row of spaced indentations adjacent said reservoir.

3. A chromatographic developing apparatus as described in claim 1 wherein said at least one additional indentation consists of a single-elongated transversely extending indentation adjacent said reservoir.

4. A chromatographic-developing apparatus as described in claim 2 wherein each of said wall members has a longitudinally extending channel in its interior face on each side of each longitudinal row of spaced indentations.

5. A chromatographic-developing apparatus as described in claim 3 wherein each of said wall members has a longitudinally extending channel in its interior face on each side of each longitudinal row of spaced indentations.

6. A chromatographic-developing apparatus as described in claim 4 wherein each of said wall members has a transversely extending channel in its interior face communicating with said longitudinally extending channels and located adjacent said transverse row of spaced indentations on the side thereof which is nearest to the open end of said chamber.

7. A chromatographic-developing apparatus as described in claim 5 wherein each of said wall members has a transversely extending channel in its interior face communicating with said longitudinally extending channels and located adjacent said elongated transversely extending indentation on the side thereof which is nearest to the open end of said chamber.

8. A chromatographic-developing apparatus as described in claim 6 including a plurality of small apertures in at least one of said wall members located so as to permit introduction onto the chromatographic sheet of a material to be subjected to chromatographic development.

9. A chromatographic-developing apparatusas described in claim 7 including a plurality ofsmall apertures'in at least one of said wall members located so as to permit introduction onto the chromatographic sheet of a material to be subjected to 

